1. Field
Embodiments of the invention relate to the field of hydrogen storage.
2. Background
The widespread use of fossil fuels for energy and for powering internal combustion engine vehicles has created significant air quality problems in much of the industrialized world. Air pollution in turn is related to numerous health and environmental problems. A variety of alternative energy sources, such as nuclear, solar, geothermal and wind power have been proposed to reduce dependence on fossil fuels. However, drawbacks exist for each of these alternative energy sources.
One of the most promising fossil fuel alternatives is hydrogen. Hydrogen can be combined with oxygen via combustion, or through fuel cell mediated oxidation/reduction reactions, to produce heat, or electrical power. After many years of development, hydrogen-based fuel cells are a viable source of energy and currently offer a number of advantages over petroleum-based internal combustion engines, and the like. Often hydrogen-based fuel cells are more efficient, operate with less friction, operate at lower temperatures, are less polluting, do not emit carbon dioxide (a suspected greenhouse gas), are quieter, etc. As a fuel, hydrogen offers a number of advantages including being abundant, affordable, clean, renewable, and having favorable energy density. The primary product of this reaction—water—is non-polluting and can be recycled to regenerate hydrogen and oxygen.
Unfortunately, existing approaches for storing, distributing, and recovering hydrogen are extremely limiting, and are a significant impediment to the widespread utilization of hydrogen fuel, and the realization of the associated advantages. To illustrate some of the problems, consider one of the more prevalent approaches based on pressurized tanks or cylinders to store gaseous or liquefied hydrogen.
This approach involves producing hydrogen gas, liquefying or pressurizing the hydrogen into a pressurized cylinder, shipping the cylinders to the point of use, and releasing the hydrogen from the cylinders. Due to hydrogen's flammability characteristics (e.g., flammability over a wide range of concentrations in air, and low spark temperatures), the storage, distribution, and use of hydrogen in such tanks is highly regulated and controlled. In order to provide improved safety, and due to the high pressures involved, the tanks are often heavy, contain specialized explosion-proof components, and are correspondingly expensive. Nevertheless, even with these precautions, there is still a significant risk that hydrogen may be released, and explode, during loading, unloading, or distribution. Such risks render the approach generally unfavorable for powering motorized vehicles. Accordingly, the costs and dangers associated with these prior art techniques for storing and distributing hydrogen are prohibitive, and limit the utilization of hydrogen as fuel.
Thus, the potential for using hydrogen as a fuel is great, but there are significant and limiting problems with conventional approaches for storing, distributing, and recovering hydrogen.